The types and amount of contaminants in water, especially potable water, are often monitored to ensure the water can safely be consumed. Since a large number of volatile organic compounds are toxic and carcinogenic, they are among the compounds often monitored. Traditionally, volatile organic compounds are monitored using a purge and trap technique. This method is required by the United States Environmental Protection Agency for monitoring many of the regulated hazardous substances in water.
The purge and trap technique consists of placing a water sample in a gas tight vessel and contacting this sample with an inert gas. The inert gas purge extracts the volatile organic compounds from the aqueous phase into the gaseous phase. The inert gas with the volatile organic compounds is then passed over an adsorbent which traps the volatile organic compounds, thereby allowing the purge gas to be separated from the volatile organic compounds. This process, although effective, is not capable of operating in zero gravity environment (hereafter referred to as zero gravity compatible). The liquid and gas phases are not readily separated due to the lack of gravity.
What is needed in the art is a technique for purge and trap sample preparation for volatile organic compounds in an aqueous sample which can be automated and can function in a zero gravity environment.